• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Survey: Aikido distortion

I built the Broskie cathode follower in 2 versions... just hearing it, I don't know if it is better than the aikido, so different with feedback etc.

It is shocking no more diyers are into building the aikido or a modified version, I could send them the schematic... it is an almost 0 distortion 0 feedback preamp.

What I find even more shocking is how much difference a 6sn7gt NOS makes in any gain position, how better the sound is, including in feedback designs. Like glasses on/off.
 
Listening to the Broskie cathode follower now with AKM dac... and then I switched back to a normal good dac.... its been months and my tweaked dac with last minute modifications (since 5 years working on it) was only compared to my turntable....

Now, it is extremely shocking how poor normal dacs sounds... i am totally unable to explain how just a good dac output can do this...

1. the resolution is at least 10 times better... with my tube stage which has a dual mono supply with dual 50mA 10H chokes and the best 6dj8 possible to find, the best output and input caps possible to find, best powr supply ez81 rectifier with input resistors etc...

220uf caps per section + 2 main film power filter caps with a small resistor, AC heaters all over under 90db noise!

2. now the bass, and the high are totally pure and the midrange has a left over of grain, probably from the not perfect loading resistors, I am working on it still....

3. The most amazing is how veiled and muffled the original dacs with opamps sound... it is shocking how bad the sound is...

4. the dynamics are way better! you can hear everything, with opamps you hear almost nothing, a fake sound.

5. singing is very intelligible now, I can hear accent on the 'pst' ssst' tksss tssst 'bnnn' 'ktnn' 'pht' 'shab' 'ye' 'bee' etc clearly in the mix, it is DAY and NIGHT.
 
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I built the Broskie cathode follower in 2 versions... just hearing it, I don't know if it is better than the aikido, so different with feedback etc.

It is shocking no more diyers are into building the aikido or a modified version, I could send them the schematic... it is an almost 0 distortion 0 feedback preamp.

What I find even more shocking is how much difference a 6sn7gt NOS makes in any gain position, how better the sound is, including in feedback designs. Like glasses on/off.

So aikido is not almost 0 distortion, but colors nicely.
 
Yes, the Aikido, with superior input tubes (nos of the best types) is very good and tolerant of power supply.

It doesn't requires expensive parts etc, except you can maximize the first tube and output capacitors. It is so good that you can almost hear the 'coloration' of the volume control.... I changed volume controls on amps with no difference, on the Aikido, it would justify a resistor with gold contact volume control.
 
The Aikido is a good project for someone with a handful of really nice older stock tubes to show off a little. Use some fancy physically huge coupling caps, some nice clear top 6CG7/6FQ7 or red base 6SN7 as the gain tube, and a nice 6DJ8/6922 type as the follower. Splurge on a pair of fancy output capacitors. Gold plated solid-machined RCA output jacks. Nice polished chassis, some fancy hardwood side plates. You can have a really killer looking piece of gear for a couple hundred bucks, without devolving too far into the snake-oil practices one would expect from such pieces of equipment. ;)

A personal favorite variant of mine was using subminiature 6111 tubes in both positions, and running it into my Szekeres mosfet follower for running some small DIY computer speakers. I ran it at ~150 volt supply and DC heaters. Dead silent at idle and nice, clean sound at the listening volume I used them at. Cool way to use some cute little quality tubes.
 
The Aikido is a good project for someone with a handful of really nice older stock tubes to show off a little. Use some fancy physically huge coupling caps, some nice clear top 6CG7/6FQ7 or red base 6SN7 as the gain tube, and a nice 6DJ8/6922 type as the follower. Splurge on a pair of fancy output capacitors. Gold plated solid-machined RCA output jacks. Nice polished chassis, some fancy hardwood side plates. You can have a really killer looking piece of gear for a couple hundred bucks, without devolving too far into the snake-oil practices one would expect from such pieces of equipment. ;)

A personal favorite variant of mine was using subminiature 6111 tubes in both positions, and running it into my Szekeres mosfet follower for running some small DIY computer speakers. I ran it at ~150 volt supply and DC heaters. Dead silent at idle and nice, clean sound at the listening volume I used them at. Cool way to use some cute little quality tubes.
I see you are fully dedicated to tubes. Good !!!
 
Good morning Lingwendil:
Coould you tell me more about the 6dj8 as the follower stage. I have my aikido set to regulated 300v with 6sn7 tubes in both stages right now and would be keen to try another tube as the output stage.

Thanks
6DJ8 as the output stage would give more drive capability for long cables or even headphones of moderate impedance. I used them in an Aikido with some 300 ohm headphones and they worked better than expected.

I see you are fully dedicated to tubes. Good !!!
yes ;)

I've been building with them for about fifteen years. They aren't perfect, but I think pursuing nice low-distortion designs that perform well is a fun hobby. Especially small simple projects like the Aikido where you can really have fun on the chassis design.

I actually rarely build anything other than push-pull amps nowadays- maybe I should build up another Aikido after I finish the 6V6 Salas line preamp PCBs I drew up 🤔 It would be interesting to compare them.